bcache: update document info

There is no return in continue_at(), update the documentation.
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Acked-by: NColy Li <colyli@suse.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

drivers/md/bcache/closure.c

@@ -112,7 +112,7 @@ bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
 EXPORT_SYMBOL(closure_wait);
 
 /**
- * closure_sync - sleep until a closure a closure has nothing left to wait on
+ * closure_sync - sleep until a closure has nothing left to wait on
  *
  * Sleeps until the refcount hits 1 - the thread that's running the closure owns
  * the last refcount.

drivers/md/bcache/closure.h

@@ -31,7 +31,8 @@
  * passing it, as you might expect, the function to run when nothing is pending
  * and the workqueue to run that function out of.
  *
- * continue_at() also, critically, is a macro that returns the calling function.
+ * continue_at() also, critically, requires a 'return' immediately following the
+ * location where this macro is referenced, to return to the calling function.
  * There's good reason for this.
  *
  * To use safely closures asynchronously, they must always have a refcount while